There exists a need for post-mix containers, most notably, in the cosmetic, household products, health, and beverage markets. Generally, a post-mix container has independent vessels or storage compartments that can contain various combinations of liquids, powders, or pastes that are stored in a separated state until the user or consumer elects to combine and use the product. Post-mix containers are useful in applications where keeping product ingredients separate until utilization extends the storage life or enhances product effectiveness over a premixed product. Applications include, but are not limited to, storage of face creams, body lotions, skin cleaners, shampoos, conditioners, hair coloring, cleaning products, air fresheners, paints, vitamin drinks, power drinks, weight loss mixtures, fruit drinks, tonics, cocktails, baby formula, and milk beverages.
While many different approaches have attempted to address the demand for post-mix containers, most approaches utilize two separate containers that require the consumer to connect together before mixing. For example, U.S. Pat. No. 5,647,481 to Hundertmark et al. discloses a two-container design whereby the user must remove a screw-on cap at the top opening of the bottom container and then insert the bottom container into the top container before threading the two containers together in order to remove the plug in the bottom of the top container. Therefore, the disclosed two-container design is not assembled and shipped ready to use and, hence, needs assembly by the consumer before use.
Other post-mix containers that do not require consumer assembly before use are often not practical or cost effective to manufacture. For example, U.S. Pat. No. 6,126,032 to Herzog et al. discloses a two-component container with a stopper located in the opening of the bottom container. The stopper is ejected by an ejector as the bottom and top container are threaded together. However, the top container would have to either be filled from its top nozzle while the bottom container is inserted sufficiently to seal the bottom of the top container, or filled from the bottom with the bottom container being required to be inserted immediately following. In either case, the two-component container disclosed is not practical for mass production. A similar two-component container with a single plug is disclosed in U.S. Pat. No. 3,443,726, to Muller et al. The disclosed container has a single plug, with a knockout portion therein, that seals the top container. Since the bottom container is not sealed until it is mated with the top container, the two containers must be connected promptly after filling.
Accordingly, a long felt need exist for a post-mix container that has independently sealed compartments; needs no assembly by the consumer before use; is intuitive to use; can be filled, assembled, and shipped ready to use; is tamper resistant; is reliable and does not leak when mixing the contents; can be provided with a means to prevent the separation of the containers after post-mixing; and is cost effective to mass produce.